CsvOpenRead(String, Char, Encoding, Boolean, CsvOpts) Method

Opens a CSV file for reading.

Definition

Namespace: FolkerKinzel.CsvTools
Assembly: FolkerKinzel.CsvTools (in FolkerKinzel.CsvTools.dll) Version: 2.0.1+2345335399184346d9b2cc992ed5c814406052c1

C#

public static CsvReader OpenRead(
	string filePath,
	char delimiter = ',',
	Encoding? textEncoding = null,
	bool isHeaderPresent = true,
	CsvOpts options = CsvOpts.Default
)

VB

Public Shared Function OpenRead ( 
	filePath As String,
	Optional delimiter As Char = ","C,
	Optional textEncoding As Encoding = Nothing,
	Optional isHeaderPresent As Boolean = true,
	Optional options As CsvOpts = CsvOpts.Default
) As CsvReader

C++

public:
static CsvReader^ OpenRead(
	String^ filePath, 
	wchar_t delimiter = L',', 
	Encoding^ textEncoding = nullptr, 
	bool isHeaderPresent = true, 
	CsvOpts options = CsvOpts::Default
)

F#

static member OpenRead : 
        filePath : string * 
        ?delimiter : char * 
        ?textEncoding : Encoding * 
        ?isHeaderPresent : bool * 
        ?options : CsvOpts 
(* Defaults:
        let _delimiter = defaultArg delimiter ','
        let _textEncoding = defaultArg textEncoding null
        let _isHeaderPresent = defaultArg isHeaderPresent true
        let _options = defaultArg options CsvOpts.Default
*)
-> CsvReader

Parameters

filePath String: File path of the CSV file.
delimiter Char (Optional): The field separator character.
textEncoding Encoding (Optional): The text encoding to be used to read the CSV file or null for UTF8.
isHeaderPresent Boolean (Optional): true, to interpret the first line as a header, otherwise false.
options CsvOpts (Optional): Options for reading the CSV file.

Return Value

CsvReader
A CsvReader that allows you to iterate through the CSV data.

Remarks

The method arguments can be determined automatically with CsvAnalyzer - or use OpenReadAnalyzed(String, Encoding, Header, Boolean, Int32).

When importing CSV data from Excel, the appropriate arguments can be determined with GetExcelArguments.

Example

Note

In the following code examples - for easier readability - exception handling has been omitted.

C#

using FolkerKinzel.CsvTools;

namespace Examples;

internal static class DisableCachingExample
{
    public static void DisableCachingSideEffects(string filePath)
    {
        string[][] friends = [
                                ["Name", "City"],
                                ["Ingrid","Berlin"],
                                ["Joyce","New York"],
                                ["Horst","Hamburg"],
                                ["John","New York"],
                             ];
        friends.SaveCsv(filePath);

        Console.WriteLine("Which friends live in New York?: ");
        Console.Write("  Determine with cache enabled:  ");

        // Caching is enabled by default.
        using (CsvReader csv = Csv.OpenRead(filePath))
        {
            foreach (CsvRecord record in
                // ToArray() caches the results:
                csv.Where(x => x["City"].Span.Equals("New York", StringComparison.Ordinal)).ToArray())
            {
                Console.Write(record["Name"]);
                Console.Write(' ');
            }

            Console.WriteLine();
        }

        Console.Write("  Determine with cache disabled: ");

        // If you set the flag CsvOpts.DisableCaching and then try to cache the data,
        // you will get the wrong results:
        using (CsvReader csv = Csv.OpenRead(filePath,
                                            options: CsvOpts.Default.Set(CsvOpts.DisableCaching)))
        {
            foreach (CsvRecord record in
                // NOTE: Removing ".ToArray()" would cause the correct results.
                csv.Where(x => x["City"].Span.Equals("New York", StringComparison.Ordinal)).ToArray())
            {
                Console.Write(record["Name"]);
                Console.Write(' ');
            }
        }
    }
}
/*
Console Output:

Which friends live in New York?:
  Determine with cache enabled:  Joyce John
  Determine with cache disabled: John John
*/

Exceptions

ArgumentNullException	filePath is null.
ArgumentException	filePath is not a valid file path.
ArgumentOutOfRangeException	delimiter is either the double quotes " or a line break character ('\r' or '\n').
IOException	I/O error.